Added "I" and "I am".

It will become clear if you try to pronounce 'od mnie' :)

You replace 'od' with 'ode' only in two cases

1. In front of 'mnie' - 'ode mnie' not 'od mnie'

2. In the Lord's prayer: 'nas zbaw ode złego' - 'deliver us from evil'

Source: http://sjp.pwn.pl/szukaj/ode.html

because it needs to be complicated. And yes "od mnie " is just wrong

https://en.wiktionary.org/wiki/ode#Polish

I think "smaller," as I hear it used, usually emphasizes not height but weight. One would be unlikely to use it of a much taller person, but someone of similar height but lower body weight might be described as smaller.